1. Technical Field
The present disclosure relates to a transmission method and a reception method with a transmitter and a receiver, in which a multi-antenna is used.
2. Description of the Related Art
Conventionally, for example, there is a communication method called MIMO (Multiple-Input Multiple-Output) as a communication method in which a multi-antenna is used.
In the multi-antenna communication typified by MIMO, at least one series of transmitted data is modulated, and modulated signals are simultaneously transmitted at an identical frequency (common frequency) from different antennas, which allows enhancement of data reception quality and/or data communication rate (per unit time).
FIG. 72 is a view illustrating an outline of a spatial multiplex MIMO scheme. In the MIMO scheme of FIG. 72, configuration examples of a transmitter and a receiver are illustrated for two transmitting antennas (TX1 and TX2), two receiving antennas (RX1 and RX2), and two transmitted modulated signals (transmission streams).
The transmitter includes a signal generator and a radio processor. The signal generator performs communication path coding of the data to perform MIMO precoding processing, and generates two transmitted signals z1(t) and z2(t) that can simultaneously be transmitted at an identical frequency (common frequency). The radio processor multiplexes each transmitted signal in a frequency direction as needed basis, namely, performs a multi-carrier modulation (for example, OFDM scheme)), and inserts a pilot signal that is used when the receiver estimates a transmission path distortion, a frequency offset, and a phase distortion. (Alternatively, the pilot signal may be used to estimate another distortion, or the pilot signal may be used to detect a signal in the receiver. A usage mode of the pilot signal in the receiver is not limited to the above estimations or the signal detection.) The transmitting antenna transmits z1(t) and z2(t) using two antennas (TX1 and TX2).
The receiver includes receiving antennas (RX1 and RX2), a radio processor, a channel variation estimator, and a signal processor. Receiving antenna (RX1) receives the signals transmitted from two transmitting antennas (TX1 and TX2) of the transmitter. The channel variation estimator estimates a channel variation using the pilot signal, and supplies an estimated value of the channel variation to the signal processor. Based on channel values estimated as the signals received by the two receiving antennas, the signal processor restores pieces of data included in z1(t) and z2(t), and obtains the pieces of data as one piece of received data. The received data may be a hard decision value of “0” and “1” or a soft decision value such as a log-likelihood or a log-likelihood ratio.
Various coding methods such as a turbo code and an LDPC (Low-Density Parity-Check) code are used as the coding method (NPLs 1 and 2).